As shown in FIG. 1, a refrigerator 1 is an apparatus for storing food at low temperature, and includes a cabinet 10 constituting a receiving space 20 for receiving food, such as a refrigerating chamber and a freezing chamber, a door (not shown) opening and closing the refrigerating chamber and the freezing chamber, and a mechanical portion (not shown) constituting a refrigerant cycle and maintaining the received food at low temperature.
The cabinet 10 is provided with an insulation material to enhance cooling insulation effect, wherein the insulation material is filled between an exterior surface constituting appearance and an interior surface constituting a receiving space. To this end, as shown in FIG. 2, a polyurethane foam solution is injected between the interior surface and the exterior surface of the assembled cabinet and then foamed by heating to form a polyurethane foam 25. However, the polyurethane foam 25 has a limitation in improving insulation efficiency due to air for transferring heat, contained therein and its thermal conductive characteristics.
Accordingly, to improve cooling efficiency and energy efficiency by shielding heat exchange between the receiving space inside the refrigerator and the outside of the refrigerator, as shown in FIG. 3, an improved insulation structure has been recently used, in which a vacuum insulation panel 40 is additionally formed between the exterior surface and the interior surface of the cabinet in addition to the insulation portion 25.
In more detail, the vacuum insulation panel 40, as shown in FIG. 4, includes a core material 41 formed of panels woven from organic glass fiber and deposited, having a vacuum state between the panels, a sealing cover 42 formed to surround the core material 41 to maintain the vacuum state of the core material 41, and a getter 30 formed to maintain insulation efficiency for a sufficient time period by removing gas component flowed through the sealing cover 42.
At this time, the vacuum insulation panel 40 can isolate the core material 41 from the outside by surrounding the core material 41 with the sealing cover 42 under the vacuum state and heating-fusion bonding two opposing surfaces of the sealing cover 42. Also, to more completely isolate the core material 41 from the outside, the two surfaces of the sealing cover 42 are heating-fusion bonded at a long length, and thus an extension sealing portion 42 protruded from the core material 41 is formed. When the aforementioned vacuum insulation panel 40 is inserted into the cabinet 10, as shown in FIG. 5, the extension sealing portion 42 protruded from the core material 41 and heating-fusion bonded is provided in a folded state.
The getter 30, as shown in FIG. 6, is manufactured by SEAS, and includes a getter container 31 provided with an opening having a receiving portion therein, a bottom part 32 formed on the bottom of the receiving portion inside the getter container 31 in a plate shape, a center part 33 formed on the bottom part 32, and a film 34 formed around the center part 33. And the bottom part 32, the center part 33 and the film 34 are made of CoO, BaLi4 alloy and BaO respectively.
In other words, since the getter 30 contains components such as Ba, Zr, Ti, V and Co, which are expensive, the cost required for manufacture of the getter increases. Also, if the above components are exposed at a room temperature, a problem occurs in that heat is generated at high temperature or risk of explosion exists.
First of all, in a state that gas is rarely generated from the core material 41, although thermal conductivity of water between gas and water permeated into the vacuum insulation panel 40 through the sealing cover 42 is 10 times higher than that of gas, the related art getter is designed to remove gas only for a vacuum range, whereby there is limitation in maintaining insulation efficiency of the vacuum insulation panel 40 for a long time.
Furthermore, the core material 41, as disclosed in the International Patent Application No. PCT/JP2004/11709, may be manufactured by spraying water into a bulk fiber and pressurizing the bulk fiber at a temperature of 380° C. to control a thickness. Alternatively, the core material 41, as disclosed in the International Patent Application No. PCT/JP2003/0099552, may be manufactured at a proper thickness by spraying an organic or inorganic binder into a bulk fiber to generate binding power between glass fibers.
However, when the core material 41 is manufactured using the glass fiber, the process of heating the glass fiber or coating the binder is necessarily required. In this case, the core material 41 is manufactured at high cost in comparison with the case where the core material is manufactured using glass wool. Moreover, in a state that the vacuum insulation panel is disposed in a predetermined position, gas is likely to be leaked out of the organic or inorganic binder to cause destroy the vacuum state of the vacuum insulation panel. For this reason, another problem occurs in that an additional getter is required to prevent the vacuum state of the vacuum insulation panel from being destroyed.
Furthermore, if bulk fiber is used as a core material for the vacuum insulation panel, its thickness should be compressed five times or greater. For this reason, a problem occurs in that use of films for the sealing cover increases and it is not easy to handle the vacuum insulation panel.